Answer: A. U.S. Sailors had been briefly arrested.
Explanation: In an incident known as the “Dolphin incident”, the U.S. President, Wilson, claimed that the Victoriano Huerta led administration allowed the arrest of some U.S. sailors while they were on an assignment to provide more supplies to the U.S.S Dolphin.
When his demands for an apology were met with the cold shoulder, President Wilson sent the U.S. Navy to occupy the port of Veracruz.
In addition, the President saw it as a threat that Germany was going to support the Mexican government by supplying them with weapons, despite the embargo.